Campylobacter bacteria are a major cause of foodborne diarrhoeal illness in humans and are the most common bacteria that cause gastroenteritis worldwide. In developed and developing countries, they cause more cases of diarrhoea than foodborne Salmonella. The high incidence of Campylobacter diarrhoea, as well as its duration and possible sequelae, makes it highly important from a socio-economic perspective. In developing countries, Campylobacter infections in children under the age of two years are especially frequent, sometimes resulting in death.

Campylobacter are mainly spiral-shaped, S-shaped or curved, rod-shaped bacteria. Currently, there are 17 species and 6 subspecies assigned to the genus Campylobacter, of which the most frequently reported in human diseases are C. jejuni (subspecies jejuni) and C. coli. Other species such as C. lari and C. upsaliensis have also been isolated from patients with diarrhoeal disease, but are reported less frequently. Most species prefer a micro-aerobic atmosphere (containing 3-10% oxygen) for growth. Some species tend to favour an anaerobic environment (containing little or no oxygen), although they will also grow under micro-aerobic conditions.

The disease

Campylobacteriosis is the disease caused by the infection with Campylobacter. The onset of disease symptoms usually occurs two to five days after infection with the bacteria, but can range from one to ten days.

The most common clinical symptoms of Campylobacter infections include diarrhoea (frequently with blood in the faeces), abdominal pain, fever, headache, nausea, and/or vomiting. The symptoms typically last three to six days.

Death from Campylobacteriosis is rare and is usually confined to very young or elderly patients, or to those already suffering from another serious disease such as AIDS.

Complications such as bacteraemia (presence of bacteria in the blood), hepatitis, pancreatitis (infections of liver and pancreas, respectively), and miscarriage have all been reported with various degrees of frequency. Post-infection complications may include reactive arthritis (painful inflammation of the joints which can last for several months) and neurological disorders such as Guillain-Barré syndrome, a polio-like form of paralysis that can result in respiratory and severe neurological dysfunction or death in a small number of cases.

Sources and transmission

Campylobacter species are widely distributed in most warm-blooded animals. They are prevalent in food animals such as poultry, cattle, pigs, sheep, ostriches and shellfish; and in pets, including cats and dogs.

The main route of transmission is generally believed to be foodborne, via undercooked meat and meat products, as well as raw or contaminated milk. Contaminated water or ice is also a source of infection. A proportion of cases occur following contact with contaminated water during recreational activities.

Campylobacteriosis is a zoonosis, a disease transmitted to humans from animals or animal products. Most often, carcasses or meat are contaminated by Campylobacter from faeces during slaughtering. In animals, Campylobacter seldom causes disease.

The relative contribution of each of the above sources to the overall burden of disease is unclear but consumption of undercooked contaminated poultry is believed to be a major contributor. Since common-source outbreaks account for a rather small proportion of cases, the vast majority of reports refer to sporadic cases, with no easily discernible pattern.

Estimating the importance of all known sources is therefore extremely difficult. In addition, the wide occurrence of Campylobacter also hinders the development of control strategies throughout the food chain. However, in countries where specific strategies have been put in place to reduce the prevalence of Campylobacter in live poultry, a similar reduction in human cases is observed.

Treatment

Treatment is not generally required, except electrolyte replacement and rehydration. Antimicrobial treatment (erythromycin, tetracycline, quinolones) is recommended in invasive cases (when bacteria invade the intestinal mucosa cells and damage the tissues) or to eliminate the carrier state (the condition of people who harbour Campylobacter in their bodies and keep shedding the bacteria while remaining asymptomatic).

Prevention methods

Prevention is based on control measures at all stages of the food chain, from agricultural production on a farm, to processing, manufacturing and preparation of foods both commercially and domestically.

In countries without adequate sewage disposal systems, faeces and articles soiled with faeces may need to be disinfected before disposal.

Measures to reduce the prevalence of Campylobacter in poultry include enhanced biosecurity to avoid transmission of Campylobacter from the environment to the flock of birds on the farm. This control option is feasible only where birds are kept in closed housing conditions.

Good hygienic slaughtering practices reduce the contamination of carcasses by faeces, but will not guarantee the absence of Campylobacter from meat and meat products. Education in hygienic food handling for abattoir workers and raw meat producers is essential to keep contamination to a minimum.

Prevention methods against infection in domestic kitchens are similar to those used against other foodborne bacterial diseases.

Bactericidal treatment, such as heating (e.g. cooking or pasteurization) or irradiation is the only effective method of eliminating Campylobacter from contaminated foods.

WHO response

In partnership with other stakeholders, WHO is developing policies that will further promote the safety of food. These policies cover the entire food chain from production to consumption and will make use of different types of expertise.

WHO promotes the strengthening of food safety systems, promoting good manufacturing practices and educating retailers and consumers about appropriate food handling and avoiding contamination. Education of consumers and training of food handlers in safe food handling is one of the most critical interventions in the prevention of foodborne illnesses.